July 16, 2012 -- According to the conventional wisdom,
urinary incontinence is a problem of middle-aged and older women, especially those who've had a baby. But a study out today suggests even young women who've never been pregnant could suffer from the problem.

The Australian researchers say their study is the first to look at the rate of urinary incontinence in this younger population. They recruited healthy young women aged 16 to 30 on university campuses and at health clinics. The scientists asked the women to complete questionnaires about urinary incontinence during routine activities or sports, psychological well-being, physical activity, and health. They ended up with usable questionnaires from just over 1,000 women whose average age was 22.

About one in eight of the young women reported they'd experienced urinary incontinence.

Unlike previous studies, the researchers found no association between urinary incontinence and age, body mass index, physical activity, or past urinary tract infections. They say that could be due to the fact that the women in their study were relatively young, physically active and, for the most part, of normal body weight.

Women who had been sexually active but did not report use of oral contraceptives were more likely to report urinary incontinence than women with no history of sexual activity.

Urinary incontinence was also associated with lower psychological well-being. In previous research, "younger women have been shown to be subject to greater distress and restriction in activities from UI (urinary incontinence) than older women," the scientists write.

Researcher Susan Davis, PhD, chair of women's health in the Monash University department of medicine at the Alfred Hospital in Melbourne, says she and her collaborators had suspected that some women might be predisposed to incontinence without being pregnant.

"Our study shows that this is clearly the case," Davis says in an email. The reasons aren't clear, though, she says. "Anatomy. Genetics. Who knows?"

Possible reasons for the link between being sexually active and having urinary incontinence include the effects of intercourse and altered bacteria in the urogenital tract, according to the researchers.

Although other studies suggest urinary incontinence runs in families, University of Rochester urogynecologist Gunhilde Buchsbaum MD says, "We do not have good genetic evidence."

Clues From Young Women

Davis' study has made her consider doing her own research in younger women who've never been pregnant, Buchsbaum says.

"We are in some ways so focused on childbirth being the main risk factor for urinary incontinence that we neglect women who have not given birth," says Buchsbaum, who has shown that older nuns who've never been pregnant deal with incontinence. "We know so little about the pathophysiology (of incontinence). Looking at really young women might help us to understand things a little bit further."

Emerging evidence shows that incontinence before conception predisposes women to pregnancy-related urinary incontinence, Davis and the other researchers write.

Buchsbaum says she has seen patients as young as 14 and 15 who are dealing with stress incontinence, which older women know is what sometimes happens when they cough or sneeze. Her youngest patients are usually involved in sports or cheerleading, Buchsbaum says. "They leak quite a bit."

An ideal study of urinary incontinence would begin with teenagers and follow them to age 50 or 60, she says. That's not possible with the young women Davis studied, because although they provided demographic information, they were not asked to put their names on the questionnaires.